Planting technique of Dahlia

Dahlia is known as one of the most famous flowers in the world, mainly because of its long flowering period, large diameter and many flowers. in the north, it blossoms continuously at suitable temperature from May to mid-November, and blossoms most after autumn. it is very suitable for flower beds, flower paths or pre-court cluster planting, and dwarf varieties can be used as potted plants. Let's take a look at the planting techniques of Dahlia.

Growth habits of Dahlia

1. Lighting: dahlias like semi-shade, too strong sunlight affects flowering, the light time is generally 10-12 hours, when cultivating seedlings, it is necessary to avoid direct sunlight.

2. Temperature: Dahlia likes cool climate. It blossoms the largest, brightest and most prosperous in late September, but it is not resistant to frost, and the stems and leaves wither immediately after frost. During the growing period, the temperature is not strict, 8-35 ℃ can grow, 15-25 ℃ is suitable.

3. Moisture: Dahlia is not resistant to drought and waterlogging. In general, potted plants are watered when the soil is dry, so that they can see wet and dry, and can be drained in rainy days (the ground does not have to be watered frequently).

4. Soil: Dahlia is suitable to be cultivated in fertile sandy soil with loose soil and good drainage.

Split-root propagation of Dahlia

1. Time: the root-splitting propagation of Dahlia is usually between March and April in spring.

2. Sprouting: Dahlia has buds only in the root neck, so each divided root must have a budded root neck, no root neck or no bud point on the root neck can not sprout, can not be planted. If the germination point on the root neck is not obvious or difficult to identify, it can be accelerated in early spring, the roots are arranged at a dense distance in the hotbed, then the soil is obstructed, watered, given a certain temperature, and then divided after budding, each ramet has at least one bud.

3. Planting: take out the stored root, cut off each root and the bud attached to the root neck (the cut is coated with plant ash for antiseptic), and plant separately.

4. Advantages: ramet propagation is simple and easy, the survival rate is high, the plant is strong, but the propagation coefficient is not as high as the cutting method.

Cutting propagation of Dahlia

1. Land selection and land preparation: select fields with deep tillage layer, loose and fertile land, flat terrain and good drainage. Before deep ploughing, 125 kg of superphosphate per mu is applied as base fertilizer, plus 50% of sub-farmers 0.5 kg, soil disinfection, soil depth of about 15 cm, and then rake flat, do high or flat border width of 2 meters, ditch depth of 20 cm, open internal and external "three ditches" to facilitate drainage.

2. Cutting method: usually from June to August, lateral buds grow to 15 to 20 cm, combined with lateral buds cut along with sowing. The cuttings need 3 buds, leave the upper 2 buds, cut the third buds to the base of the leaves, insert the second buds into the soil, water them thoroughly, and use 50% shade net for double shade. Water one in the morning and one in the evening on a sunny day, watering continuously for half a month, and the soil moisture is kept at 90% for 3 weeks. The survival rate is very high, and it can blossom in the autumn of that year.

3. Post-cutting management: after the cuttage survived, the saturated leaching solution of compound fertilizer was applied once before and after flowering, and 400 ml mother solution was added to each back sprayer (about 12.5 kg) for extra-root topdressing. Dahlia should not be ploughed deep after rooting, so as not to damage the root tuber and prevent grass damage. Because the plant is succulent and soft, it is necessary to stand up so as not to break the stems and leaves. When the seedlings of small flowers are 15 cm high, they are topped to make the plants stout and blossom. After the flowers are taken off in time, the flowering period can be prolonged.

Seed propagation of Dahlia

1. Container selection: choose a seedling plate with a length of 50 cm, a width of 20 cm and a height of 5 cm, rinse with clean water first, and then disinfect it with 0.2% chloronitrobenzene.

2. Substrate configuration: select fine, uniform, stone-free, pollution-free, nutrient-rich and pest-free soil. It is suitable for the soil with good drainage and light saline-alkali. The selected sowing substrate is garden soil and peat, which is generally made of garden soil, humus soil and river sand, with a proportion of 2:2:1, and sterilized with 2% pentachloronitrobenzene or high temperature disinfection.

3. Sowing time: wash the sterilized seedling tray with clean water before sowing, sow immediately after water osmosis, sow in the hotbed in mid or late March, flower bed varieties are sown in late April, the seeds are all scattered on the soil surface, and the large seeds are covered with moist fine soil after sowing, and the thickness is 3 times of the seed diameter.

4. Film mulching: bamboo pole is used to cover agricultural film after sowing, leaving gaps for ventilation, which is helpful to increase soil temperature, reduce moisture, maintain soil moisture and reduce soil consolidation, so as to maintain the temperature and humidity needed for seed germination. After sowing, the seeds can germinate after about 7 days after sowing, and the soil moisture should be maintained frequently. When the seedlings grow to 4cm, the seedlings should be watered thoroughly, placed in the shade for 3-4 days, and then moved to strong light. Pay attention to timely watering to maintain soil moisture.

5. Management after sowing: watering according to soil moisture. Keep the soil dry and moist when the soil surface is slightly dry, keep it moist by immersion method. The optimum temperature for seed germination is 19: 21 ℃. It is often ventilated after sowing, which is conducive to seed germination. Dahlia seed germination needs proper shade, after the emergence of neat seedlings, gradually remove the film, and move the seedlings to a sunny place. 180 °turning box every 2-3 days is beneficial to the upright growth of seedlings.

Planting management of Dahlia

1. Coring and pruning: first, leave a single bud into a single plant to make it blossom early, leave 1-2 nodes short after flowering, and the new buds can continue to blossom. Second, for the varieties with poor branching, coring was carried out in the young stage to promote their branches, and the plants were truncated from the middle of July to the first ten days of August, and high-quality flowers were produced from September to October.

2. Build a flower net: generally, when the plant height is 20cm and 25cm, it is better to set up a net of 15cm. The net is fixed 45 centimeters above the ground.

3. Temperature management: for early flowering in early spring, it can be cultivated in the greenhouse. The temperature during the day is about 25 ℃. If it exceeds 25 ℃, it must be ventilated and cooled down. When the night is below 10 ℃, the temperature of the greenhouse should be increased.

4. Florescence control: if you need to open in winter and early spring, sunshine and temperature must be controlled. The results show that short-day sunshine and low temperature are the main factors to prevent flower bud differentiation of Dahlia. Cut flowers with large colors can be produced when the sunshine in winter is about 14 hours and the night temperature is more than 10 ℃.

5, cut flower harvest: Dahlia bloom at 3: 4 (2: 2 in summer) is the appropriate time to pick flowers, the first batch of flowers in spring leaves 2 sections cut, the second batch leaves a section cut, because of the poor water absorption of cut dahlias, it is easy to pick them in the morning or evening, insert them into water immediately after harvest, store the roots in a dry place immediately after harvest, or use sawdust to fill and store in 4.5mm 7.4 ℃.

6. Timely fertilization: Dahlia is a fertilizer-loving plant, and there must be sufficient fertilizer supply, otherwise it is easy to cause flowers to become smaller, dim color and lower ornamental. According to the growth situation, cake fertilizer should be applied for 4 times and 5 times, thin fertilizer should be applied, and fertilization is prohibited when the high temperature is more than 30 ℃ in summer.

7. Water management: the proper reduction of watering water is beneficial to control the growth of plants and make the stem of Dahlia thick, the plant short and the flowers large. Spray water on the leaf surface as much as possible under the condition that the water content is basically satisfied in summer high temperature, at least twice a day to make up for evaporation loss.

Disease and pest control of Dahlia

1. Root nodule disease

[hazard characteristics] Rhizobium is mainly caused by excessive wet soil, poor drainage and excessive air humidity, which causes root rot, resulting in plant growth retardation, leaf withering, green to yellow, and even death.

[prevention and control method] timely watering, loosening the soil and drainage, can be disinfected with 2.5k Bordeaux solution of 1purl 100 Bordeaux solution and 10g of Sailisan, with a dosage of 1kg / square meter.

2. Brown spot

[hazard characteristics] most of the diseased plants were damaged by red spiders at the same time, and the leaves had brown spots until they became grayish brown and died.

[control method] spray 0.5 °Be stone sulfur mixture, or spray 65% wettable Dysen zinc 500x solution.

3. Powdery mildew

[hazard characteristics] powdery mildew is a common disease of flower plants, which produces powdery spots on the back of leaves, which extends to the whole leaf, which can wither and defoliate leaves seriously.

[control methods] the diseased leaves can be removed in time by spraying 0.2 ~ 0.3 °be stone sulfur mixture or 40% carbendan 500 times.

4. Grey mold

[hazard characteristics] Botrytis cinerea, also known as flower rot, is the main disease of Dahlia, and the damage is the most serious in rainy season. First of all, the disease occurs on the leaves, and the disease spots often occur at the edge of the leaves, and gray mold grows when the humidity is high. The disease spot on the stem is brown and irregular, and the stem softens and collapses when it is serious.

[prevention and control methods] cut off diseased flowers, leaves and stems in time and burn them centrally. In autumn or early spring, the residual body should be thoroughly removed to reduce the source of infection, avoid planting too dense, facilitate ventilation and light, and remove stagnant water after rain. Spray 75% chlorothalonil wettable powder 1000 times or 50% carbendan wettable powder 1000 times, once every 10 days or even 3 times.

5. Mosaic virus disease

[hazard characteristics] Dahlia mosaic virus disease is the most widespread and the most serious. It is mainly spread by carrying virus, such as root tuber, aphids and leafhoppers. There is a pattern pattern on the diseased leaf, and the leaf vein becomes light green at and near it. The dysplasia of the diseased leaf affects flowering, and the plant shrinks and becomes shorter in severe cases.

[control methods] non-toxic breeding materials were selected to reduce the source of infection, virus-free seedlings were propagated by detoxification and tissue culture, and after planting, attention should be paid to controlling the transmission of insect vectors, paying attention to pastoral hygiene, and reducing the source of virus infection. spray 1000 times of 50% malathion, 1500 times of 40% dimethoate or 1500 times of 25% carbaryl.

6. Heart-eating insects

[harm characteristics] the heart-eating insects mainly eat the tender leaves and hearts of Dahlia flowers, and the summer festival is serious. The larvae drill into the stem and break the stem to kill the plant, and then transfer to another plant.

[control method] to dispose of the diseased plant in time, it can be sprayed with 1500 times liquid of parathion.

7. Aphids

[hazard characteristics] common plant pests.

[control method] it can be sprayed with 40% dimethoate 1000-1500 times or 50% aphid pine 1000 times.

8. Red spider

[hazard characteristics] damage the leaves, yellowing, falling leaves, and even the death of the whole plant.

[control method] Water can be sprayed on the leaf surface, or it can be sprayed with 40% dimethoate 1000-1500 times.

9. Dahlia borer moth

[damage characteristics] the larval damage period of Dahlia borer, also known as corn borer and drillworm, occurred from June to mid-July and from mid-August to October, especially in August and September, which happened to be the florescence of Dahlia.

[control methods] when the pest is light, the insect plant can be pruned and the larvae can be killed centrally to prevent spread. During the larval incubation period, 50% fenitrothasone emulsion 1000-1500 times can be sprayed for control. For the older larvae that have been eaten into the depths, the injection needle can be used to inject 200-500 times of fenitrothion into the wormhole.